val J =
  "[{\"name\":\"Joe\", \"age\":21, \"grade\":1.1},{\"name\":\"Sue\", \"age\":31, \"grade\":2.0},{\"name\":\"Bob\", \"age\":41, \"grade\":3.9}]" : string

val getNames = fn : ['a#{name: 'b}, 'b. 'a list -> 'b list]

val j = _ : JSON.void JSON.dyn

val vl =
  [
   {age = 21, grade = 1.1, name = "Joe"},
   {age = 31, grade = 2.0, name = "Sue"},
   {age = 41, grade = 3.9, name = "Bob"}
  ] : {age: int, grade: real, name: string} list

val nl = ["Joe", "Sue", "Bob"] : string list
